qom: Crash more nicely on object_property_get_link() failure

Pass &error_abort instead of NULL where the returned value is
dereferenced or asserted to be non-null.  Drop a now redundant
assertion.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200707160613.848843-24-armbru@redhat.com>

hw/core/platform-bus.c

@@ -22,6 +22,7 @@
 #include "qemu/osdep.h"
 #include "hw/platform-bus.h"
 #include "hw/qdev-properties.h"
+#include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 
@@ -63,9 +64,8 @@ hwaddr platform_bus_get_mmio_addr(PlatformBusDevice *pbus, SysBusDevice *sbdev,
         return -1;
     }
 
-    parent_mr = object_property_get_link(OBJECT(sbdev_mr), "container", NULL);
-
-    assert(parent_mr);
+    parent_mr = object_property_get_link(OBJECT(sbdev_mr), "container",
+                                         &error_abort);
     if (parent_mr != pbus_mr_obj) {
         /* MMIO region is not mapped on platform bus */
         return -1;

hw/ppc/spapr_drc.c

@@ -870,7 +870,8 @@ int spapr_dt_drc(void *fdt, int offset, Object *owner, uint32_t drc_type_mask)
             continue;
         }
 
-        obj = object_property_get_link(root_container, prop->name, NULL);
+        obj = object_property_get_link(root_container, prop->name,
+                                       &error_abort);
         drc = SPAPR_DR_CONNECTOR(obj);
         drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
 

hw/ppc/spapr_hcall.c

@@ -1655,7 +1655,8 @@ static void spapr_handle_transient_dev_before_cas(SpaprMachineState *spapr)
             continue;
         }
         drc = SPAPR_DR_CONNECTOR(object_property_get_link(drc_container,
-                                                          prop->name, NULL));
+                                                          prop->name,
+                                                          &error_abort));
 
         if (spapr_drc_transient(drc)) {
             spapr_drc_reset(drc);

hw/ppc/spapr_pci_nvlink2.c

@@ -358,7 +358,8 @@ void spapr_phb_nvgpu_ram_populate_dt(SpaprPhbState *sphb, void *fdt)
     for (i = 0; i < sphb->nvgpus->num; ++i) {
         SpaprPhbPciNvGpuSlot *nvslot = &sphb->nvgpus->slots[i];
         Object *nv_mrobj = object_property_get_link(OBJECT(nvslot->gpdev),
-                                                    "nvlink2-mr[0]", NULL);
+                                                    "nvlink2-mr[0]",
+                                                    &error_abort);
         uint32_t associativity[] = {
             cpu_to_be32(0x4),
             SPAPR_GPU_NUMA_ID,

ui/vnc.c

@@ -568,7 +568,7 @@ VncInfo2List *qmp_query_vnc_servers(Error **errp)
                        &info->vencrypt, &info->has_vencrypt);
         if (vd->dcl.con) {
             dev = DEVICE(object_property_get_link(OBJECT(vd->dcl.con),
-                                                  "device", NULL));
+                                                  "device", &error_abort));
             info->has_display = true;
             info->display = g_strdup(dev->id);
         }