[Qemu-devel] [PATCH] fix assertion in "info memory-devices" if memdev isn't accessible

[Igor Mammedov]

showing a memory device whose memdev is removed leads to an assert:

(qemu) object_add memory-backend-ram,id=ram0,size=128M
(qemu) device_add pc-dimm,id=d0,memdev=ram0
(qemu) object_del ram0
(qemu) info memory-devices
**
ERROR:qom/object.c:1274:object_get_canonical_path_component:\
                            assertion failed: (obj->parent != NULL)
Aborted

so check if memdev is present before calling
object_get_canonical_path() and in case it's not assign to
"memdev:" field "removed" value.

Signed-off-by: Igor Mammedov <address@hidden>
---
alternative more generic solution:
   http://patchwork.ozlabs.org/patch/453343/
---
 backends/hostmem.c       | 23 +++++++++++++++++++++++
 hw/mem/pc-dimm.c         | 15 ++++++++++++++-
 include/sysemu/hostmem.h |  1 +
 qmp.c                    |  1 +
 4 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 99e8f99..aa88691 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -227,6 +227,26 @@ static void host_memory_backend_set_prealloc(Object *obj, 
bool value,
     }
 }
 
+static void host_memory_backend_set_id(Object *obj, const char *id,
+                                       Error **errp)
+{
+    HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+
+    if (backend->id) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "id",
+                  "can't change already set value");
+        return;
+    }
+    backend->id = g_strdup(id);
+}
+
+static char *host_memory_backend_get_id(Object *obj, Error **errp)
+{
+    HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+
+    return g_strdup(backend->id);
+}
+
 static void host_memory_backend_init(Object *obj)
 {
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
@@ -237,6 +257,9 @@ static void host_memory_backend_init(Object *obj)
                                       "dump-guest-core", true);
     backend->prealloc = mem_prealloc;
 
+    object_property_add_str(obj, "id",
+                            host_memory_backend_get_id,
+                            host_memory_backend_set_id, NULL);
     object_property_add_bool(obj, "merge",
                         host_memory_backend_get_merge,
                         host_memory_backend_set_merge, NULL);
diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 39f0c97..482a7a0 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -69,6 +69,8 @@ int qmp_pc_dimm_device_list(Object *obj, void *opaque)
         DeviceState *dev = DEVICE(obj);
 
         if (dev->realized) {
+            char *mdevid, *mdevpath;
+            Object *mdev;
             MemoryDeviceInfoList *elem = g_new0(MemoryDeviceInfoList, 1);
             MemoryDeviceInfo *info = g_new0(MemoryDeviceInfo, 1);
             PCDIMMDeviceInfo *di = g_new0(PCDIMMDeviceInfo, 1);
@@ -86,7 +88,18 @@ int qmp_pc_dimm_device_list(Object *obj, void *opaque)
             di->node = dimm->node;
             di->size = object_property_get_int(OBJECT(dimm), PC_DIMM_SIZE_PROP,
                                                NULL);
-            di->memdev = object_get_canonical_path(OBJECT(dimm->hostmem));
+            mdevid = object_property_get_str(OBJECT(dimm->hostmem), "id",
+                                             &error_abort);
+            mdevpath = g_strdup_printf("/objects/%s", mdevid);
+            g_free(mdevid);
+            mdev = object_resolve_path_type(mdevpath, TYPE_MEMORY_BACKEND,
+                                            NULL);
+            if (mdev == OBJECT(dimm->hostmem)) {
+                di->memdev = object_get_canonical_path(OBJECT(dimm->hostmem));
+            } else {
+                di->memdev = g_strdup("removed");
+            }
+            g_free(mdevpath);
 
             info->dimm = di;
             elem->value = info;
diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h
index 1ce4394..63918aa 100644
--- a/include/sysemu/hostmem.h
+++ b/include/sysemu/hostmem.h
@@ -53,6 +53,7 @@ struct HostMemoryBackend {
     Object parent;
 
     /* protected */
+    char *id;
     uint64_t size;
     bool merge, dump;
     bool prealloc, force_prealloc;
diff --git a/qmp.c b/qmp.c
index c479e77..6f1cca7 100644
--- a/qmp.c
+++ b/qmp.c
@@ -649,6 +649,7 @@ void object_add(const char *type, const char *id, const 
QDict *qdict,
             }
         }
     }
+    object_property_set_str(obj, id, "id", NULL);
 
     object_property_add_child(container_get(object_get_root(), "/objects"),
                               id, obj, &local_err);
-- 
1.8.3.1