Stop accessing driver->caps directly in LXC driver

The 'driver->caps' pointer can be changed on the fly. Accessing
it currently requires the global driver lock. Isolate this
access in a single helper, so a future patch can relax the
locking constraints.

src/lxc/lxc_conf.c

@@ -59,7 +59,7 @@ VIR_ONCE_GLOBAL_INIT(virLXCConfig)
 
 
 /* Functions */
-virCapsPtr lxcCapsInit(virLXCDriverPtr driver)
+virCapsPtr virLXCDriverCapsInit(virLXCDriverPtr driver)
 {
     virCapsPtr caps;
     virCapsGuestPtr guest;
@@ -153,6 +153,33 @@ error:
 }
 
 
+/**
+ * virLXCDriverGetCapabilities:
+ *
+ * Get a reference to the virCapsPtr instance for the
+ * driver. If @refresh is true, the capabilities will be
+ * rebuilt first
+ *
+ * The caller must release the reference with virObjetUnref
+ *
+ * Returns: a reference to a virCapsPtr instance or NULL
+ */
+virCapsPtr virLXCDriverGetCapabilities(virLXCDriverPtr driver,
+                                       bool refresh)
+{
+    if (refresh) {
+        virCapsPtr caps = NULL;
+        if ((caps = virLXCDriverCapsInit(driver)) == NULL)
+            return NULL;
+
+        virObjectUnref(driver->caps);
+        driver->caps = caps;
+    }
+
+    return virObjectRef(driver->caps);
+}
+
+
 virDomainXMLOptionPtr
 lxcDomainXMLConfInit(void)
 {

src/lxc/lxc_conf.h

@@ -72,7 +72,8 @@ struct _virLXCDriver {
      * then lockless thereafter */
     virLXCDriverConfigPtr config;
 
-    /* Require lock while using. Unsafe. XXX */
+    /* Require lock to get a reference on the object,
+     * lockless access thereafter */
     virCapsPtr caps;
 
 
@@ -110,7 +111,9 @@ virLXCDriverConfigPtr virLXCDriverConfigNew(void);
 virLXCDriverConfigPtr virLXCDriverGetConfig(virLXCDriverPtr driver);
 int virLXCLoadDriverConfig(virLXCDriverConfigPtr cfg,
                            const char *filename);
-virCapsPtr lxcCapsInit(virLXCDriverPtr driver);
+virCapsPtr virLXCDriverCapsInit(virLXCDriverPtr driver);
+virCapsPtr virLXCDriverGetCapabilities(virLXCDriverPtr driver,
+                                       bool refresh);
 virDomainXMLOptionPtr lxcDomainXMLConfInit(void);
 
 static inline void lxcDriverLock(virLXCDriverPtr driver)

src/lxc/lxc_controller.c

@@ -162,7 +162,7 @@ static virLXCControllerPtr virLXCControllerNew(const char *name)
     if (VIR_STRDUP(ctrl->name, name) < 0)
         goto error;
 
-    if ((caps = lxcCapsInit(NULL)) == NULL)
+    if (!(caps = virLXCDriverCapsInit(NULL)))
         goto error;
 
     if (!(xmlopt = lxcDomainXMLConfInit()))

src/lxc/lxc_driver.c

@@ -193,16 +193,23 @@ static int lxcConnectIsAlive(virConnectPtr conn ATTRIBUTE_UNUSED)
 
 static char *lxcConnectGetCapabilities(virConnectPtr conn) {
     virLXCDriverPtr driver = conn->privateData;
+    virCapsPtr caps;
     char *xml;
 
     if (virConnectGetCapabilitiesEnsureACL(conn) < 0)
         return NULL;
 
     lxcDriverLock(driver);
-    if ((xml = virCapabilitiesFormatXML(driver->caps)) == NULL)
+    if (!(caps = virLXCDriverGetCapabilities(driver, false))) {
+        lxcDriverUnlock(driver);
+        return NULL;
+    }
+
+    if ((xml = virCapabilitiesFormatXML(caps)) == NULL)
         virReportOOMError();
     lxcDriverUnlock(driver);
 
+    virObjectUnref(caps);
     return xml;
 }
 
@@ -457,11 +464,15 @@ static virDomainPtr lxcDomainDefineXML(virConnectPtr conn, const char *xml)
     virDomainEventPtr event = NULL;
     virDomainDefPtr oldDef = NULL;
     virLXCDriverConfigPtr cfg = NULL;
+    virCapsPtr caps = NULL;
 
     lxcDriverLock(driver);
     cfg = virLXCDriverGetConfig(driver);
 
-    if (!(def = virDomainDefParseString(xml, driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (!(def = virDomainDefParseString(xml, caps, driver->xmlopt,
                                         1 << VIR_DOMAIN_VIRT_LXC,
                                         VIR_DOMAIN_XML_INACTIVE)))
         goto cleanup;
@@ -509,6 +520,7 @@ cleanup:
         virObjectUnlock(vm);
     if (event)
         virDomainEventStateQueue(driver->domainEventState, event);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return dom;
@@ -1138,17 +1150,21 @@ lxcDomainCreateXMLWithFiles(virConnectPtr conn,
                             unsigned int flags) {
     virLXCDriverPtr driver = conn->privateData;
     virDomainObjPtr vm = NULL;
-    virDomainDefPtr def;
+    virDomainDefPtr def = NULL;
     virDomainPtr dom = NULL;
     virDomainEventPtr event = NULL;
     virLXCDriverConfigPtr cfg = NULL;
+    virCapsPtr caps = NULL;
 
     virCheckFlags(VIR_DOMAIN_START_AUTODESTROY, NULL);
 
     lxcDriverLock(driver);
     cfg = virLXCDriverGetConfig(driver);
 
-    if (!(def = virDomainDefParseString(xml, driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (!(def = virDomainDefParseString(xml, caps, driver->xmlopt,
                                         1 << VIR_DOMAIN_VIRT_LXC,
                                         VIR_DOMAIN_XML_INACTIVE)))
         goto cleanup;
@@ -1198,6 +1214,7 @@ cleanup:
         virObjectUnlock(vm);
     if (event)
         virDomainEventStateQueue(driver->domainEventState, event);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return dom;
@@ -1285,6 +1302,7 @@ static int lxcNodeGetSecurityModel(virConnectPtr conn,
                                    virSecurityModelPtr secmodel)
 {
     virLXCDriverPtr driver = conn->privateData;
+    virCapsPtr caps = NULL;
     int ret = 0;
 
     lxcDriverLock(driver);
@@ -1293,12 +1311,15 @@ static int lxcNodeGetSecurityModel(virConnectPtr conn,
     if (virNodeGetSecurityModelEnsureACL(conn) < 0)
         goto cleanup;
 
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
     /* we treat no driver as success, but simply return no data in *secmodel */
-    if (driver->caps->host.nsecModels == 0
-        || driver->caps->host.secModels[0].model == NULL)
+    if (caps->host.nsecModels == 0
+        || caps->host.secModels[0].model == NULL)
         goto cleanup;
 
-    if (!virStrcpy(secmodel->model, driver->caps->host.secModels[0].model,
+    if (!virStrcpy(secmodel->model, caps->host.secModels[0].model,
                    VIR_SECURITY_MODEL_BUFLEN)) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("security model string exceeds max %d bytes"),
@@ -1307,7 +1328,7 @@ static int lxcNodeGetSecurityModel(virConnectPtr conn,
         goto cleanup;
     }
 
-    if (!virStrcpy(secmodel->doi, driver->caps->host.secModels[0].doi,
+    if (!virStrcpy(secmodel->doi, caps->host.secModels[0].doi,
                    VIR_SECURITY_DOI_BUFLEN)) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("security DOI string exceeds max %d bytes"),
@@ -1317,6 +1338,7 @@ static int lxcNodeGetSecurityModel(virConnectPtr conn,
     }
 
 cleanup:
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     return ret;
 }
@@ -1526,6 +1548,7 @@ static int lxcStateInitialize(bool privileged,
                               virStateInhibitCallback callback ATTRIBUTE_UNUSED,
                               void *opaque ATTRIBUTE_UNUSED)
 {
+    virCapsPtr caps = NULL;
     char *ld;
     virLXCDriverConfigPtr cfg = NULL;
 
@@ -1585,7 +1608,7 @@ static int lxcStateInitialize(bool privileged,
     if ((lxc_driver->activeUsbHostdevs = virUSBDeviceListNew()) == NULL)
         goto cleanup;
 
-    if ((lxc_driver->caps = lxcCapsInit(lxc_driver)) == NULL)
+    if ((virLXCDriverGetCapabilities(lxc_driver, true)) == NULL)
         goto cleanup;
 
     if (!(lxc_driver->xmlopt = lxcDomainXMLConfInit()))
@@ -1594,11 +1617,14 @@ static int lxcStateInitialize(bool privileged,
     if (!(lxc_driver->closeCallbacks = virCloseCallbacksNew()))
         goto cleanup;
 
+    if (!(caps = virLXCDriverGetCapabilities(lxc_driver, false)))
+        goto cleanup;
+
     /* Get all the running persistent or transient configs first */
     if (virDomainObjListLoadAllConfigs(lxc_driver->domains,
                                        cfg->stateDir,
                                        NULL, 1,
-                                       lxc_driver->caps,
+                                       caps,
                                        lxc_driver->xmlopt,
                                        1 << VIR_DOMAIN_VIRT_LXC,
                                        NULL, NULL) < 0)
@@ -1610,7 +1636,7 @@ static int lxcStateInitialize(bool privileged,
     if (virDomainObjListLoadAllConfigs(lxc_driver->domains,
                                        cfg->configDir,
                                        cfg->autostartDir, 0,
-                                       lxc_driver->caps,
+                                       caps,
                                        lxc_driver->xmlopt,
                                        1 << VIR_DOMAIN_VIRT_LXC,
                                        NULL, NULL) < 0)
@@ -1624,6 +1650,7 @@ static int lxcStateInitialize(bool privileged,
     return 0;
 
 cleanup:
+    virObjectUnref(caps);
     lxcDriverUnlock(lxc_driver);
     lxcStateCleanup();
     return -1;
@@ -1652,21 +1679,28 @@ static void lxcNotifyLoadDomain(virDomainObjPtr vm, int newVM, void *opaque)
 static int
 lxcStateReload(void) {
     virLXCDriverConfigPtr cfg = NULL;
+    virCapsPtr caps = NULL;
 
     if (!lxc_driver)
         return 0;
 
     lxcDriverLock(lxc_driver);
+    if (!(caps = virLXCDriverGetCapabilities(lxc_driver, false))) {
+        lxcDriverUnlock(lxc_driver);
+        return -1;
+    }
+
     cfg = virLXCDriverGetConfig(lxc_driver);
 
     virDomainObjListLoadAllConfigs(lxc_driver->domains,
                                    cfg->configDir,
                                    cfg->autostartDir, 0,
-                                   lxc_driver->caps,
+                                   caps,
                                    lxc_driver->xmlopt,
                                    1 << VIR_DOMAIN_VIRT_LXC,
                                    lxcNotifyLoadDomain, lxc_driver);
     lxcDriverUnlock(lxc_driver);
+    virObjectUnref(caps);
     virObjectUnref(cfg);
     return 0;
 }
@@ -1894,6 +1928,7 @@ lxcDomainSetSchedulerParametersFlags(virDomainPtr dom,
                                      unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     size_t i;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
@@ -1930,13 +1965,16 @@ lxcDomainSetSchedulerParametersFlags(virDomainPtr dom,
     if (virDomainSetSchedulerParametersFlagsEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
-    if (virDomainLiveConfigHelperMethod(driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (virDomainLiveConfigHelperMethod(caps, driver->xmlopt,
                                         vm, &flags, &vmdef) < 0)
         goto cleanup;
 
     if (flags & VIR_DOMAIN_AFFECT_CONFIG) {
         /* Make a copy for updated domain. */
-        vmdef = virDomainObjCopyPersistentDef(vm, driver->caps, driver->xmlopt);
+        vmdef = virDomainObjCopyPersistentDef(vm, caps, driver->xmlopt);
         if (!vmdef)
             goto cleanup;
     }
@@ -2015,6 +2053,7 @@ cleanup:
     virDomainDefFree(vmdef);
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return ret;
@@ -2035,6 +2074,7 @@ lxcDomainGetSchedulerParametersFlags(virDomainPtr dom,
                                      unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr persistentDef;
     unsigned long long shares = 0;
@@ -2070,7 +2110,10 @@ lxcDomainGetSchedulerParametersFlags(virDomainPtr dom,
         cpu_bw_status = !!rc;
     }
 
-    if (virDomainLiveConfigHelperMethod(driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (virDomainLiveConfigHelperMethod(caps, driver->xmlopt,
                                         vm, &flags, &persistentDef) < 0)
         goto cleanup;
 
@@ -2133,6 +2176,7 @@ out:
 cleanup:
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     return ret;
 }
@@ -2153,6 +2197,7 @@ lxcDomainSetBlkioParameters(virDomainPtr dom,
                             unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     size_t i;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr persistentDef = NULL;
@@ -2184,7 +2229,10 @@ lxcDomainSetBlkioParameters(virDomainPtr dom,
     if (virDomainSetBlkioParametersEnsureACL(dom->conn, vm->def, flags) < 0)
         goto cleanup;
 
-    if (virDomainLiveConfigHelperMethod(driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (virDomainLiveConfigHelperMethod(caps, driver->xmlopt,
                                         vm, &flags, &persistentDef) < 0)
         goto cleanup;
 
@@ -2242,6 +2290,7 @@ lxcDomainSetBlkioParameters(virDomainPtr dom,
 cleanup:
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return ret;
@@ -2256,6 +2305,7 @@ lxcDomainGetBlkioParameters(virDomainPtr dom,
                             unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     size_t i;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr persistentDef = NULL;
@@ -2287,7 +2337,10 @@ lxcDomainGetBlkioParameters(virDomainPtr dom,
         goto cleanup;
     }
 
-    if (virDomainLiveConfigHelperMethod(driver->caps, driver->xmlopt,
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
+    if (virDomainLiveConfigHelperMethod(caps, driver->xmlopt,
                                         vm, &flags, &persistentDef) < 0)
         goto cleanup;
 
@@ -2348,6 +2401,7 @@ lxcDomainGetBlkioParameters(virDomainPtr dom,
 cleanup:
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     return ret;
 }
@@ -4348,6 +4402,7 @@ static int lxcDomainAttachDeviceFlags(virDomainPtr dom,
                                       unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
     virDomainDeviceDefPtr dev = NULL, dev_copy = NULL;
@@ -4391,6 +4446,9 @@ static int lxcDomainAttachDeviceFlags(virDomainPtr dom,
         }
     }
 
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
     if ((flags & VIR_DOMAIN_AFFECT_CONFIG) && !vm->persistent) {
          virReportError(VIR_ERR_OPERATION_INVALID, "%s",
                         _("cannot modify device on transient domain"));
@@ -4398,7 +4456,7 @@ static int lxcDomainAttachDeviceFlags(virDomainPtr dom,
     }
 
     dev = dev_copy = virDomainDeviceDefParse(xml, vm->def,
-                                             driver->caps, driver->xmlopt,
+                                             caps, driver->xmlopt,
                                              VIR_DOMAIN_XML_INACTIVE);
     if (dev == NULL)
         goto cleanup;
@@ -4410,7 +4468,7 @@ static int lxcDomainAttachDeviceFlags(virDomainPtr dom,
          * to CONFIG takes one instance.
          */
         dev_copy = virDomainDeviceDefCopy(dev, vm->def,
-                                          driver->caps, driver->xmlopt);
+                                          caps, driver->xmlopt);
         if (!dev_copy)
             goto cleanup;
     }
@@ -4420,7 +4478,7 @@ static int lxcDomainAttachDeviceFlags(virDomainPtr dom,
             goto cleanup;
 
         /* Make a copy for updated domain. */
-        vmdef = virDomainObjCopyPersistentDef(vm, driver->caps, driver->xmlopt);
+        vmdef = virDomainObjCopyPersistentDef(vm, caps, driver->xmlopt);
         if (!vmdef)
             goto cleanup;
         if ((ret = lxcDomainAttachDeviceConfig(vmdef, dev)) < 0)
@@ -4460,6 +4518,7 @@ cleanup:
     virDomainDeviceDefFree(dev);
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return ret;
@@ -4479,6 +4538,7 @@ static int lxcDomainUpdateDeviceFlags(virDomainPtr dom,
                                       unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
     virDomainDeviceDefPtr dev = NULL, dev_copy = NULL;
@@ -4529,8 +4589,11 @@ static int lxcDomainUpdateDeviceFlags(virDomainPtr dom,
          goto cleanup;
     }
 
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
     dev = dev_copy = virDomainDeviceDefParse(xml, vm->def,
-                                             driver->caps, driver->xmlopt,
+                                             caps, driver->xmlopt,
                                              VIR_DOMAIN_XML_INACTIVE);
     if (dev == NULL)
         goto cleanup;
@@ -4542,7 +4605,7 @@ static int lxcDomainUpdateDeviceFlags(virDomainPtr dom,
          * to CONFIG takes one instance.
          */
         dev_copy = virDomainDeviceDefCopy(dev, vm->def,
-                                          driver->caps, driver->xmlopt);
+                                          caps, driver->xmlopt);
         if (!dev_copy)
             goto cleanup;
     }
@@ -4552,7 +4615,7 @@ static int lxcDomainUpdateDeviceFlags(virDomainPtr dom,
             goto cleanup;
 
         /* Make a copy for updated domain. */
-        vmdef = virDomainObjCopyPersistentDef(vm, driver->caps, driver->xmlopt);
+        vmdef = virDomainObjCopyPersistentDef(vm, caps, driver->xmlopt);
         if (!vmdef)
             goto cleanup;
         if ((ret = lxcDomainUpdateDeviceConfig(vmdef, dev)) < 0)
@@ -4585,6 +4648,7 @@ cleanup:
     virDomainDeviceDefFree(dev);
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return ret;
@@ -4596,6 +4660,7 @@ static int lxcDomainDetachDeviceFlags(virDomainPtr dom,
                                       unsigned int flags)
 {
     virLXCDriverPtr driver = dom->conn->privateData;
+    virCapsPtr caps = NULL;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr vmdef = NULL;
     virDomainDeviceDefPtr dev = NULL, dev_copy = NULL;
@@ -4645,8 +4710,11 @@ static int lxcDomainDetachDeviceFlags(virDomainPtr dom,
          goto cleanup;
     }
 
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
     dev = dev_copy = virDomainDeviceDefParse(xml, vm->def,
-                                             driver->caps, driver->xmlopt,
+                                             caps, driver->xmlopt,
                                              VIR_DOMAIN_XML_INACTIVE);
     if (dev == NULL)
         goto cleanup;
@@ -4658,7 +4726,7 @@ static int lxcDomainDetachDeviceFlags(virDomainPtr dom,
          * to CONFIG takes one instance.
          */
         dev_copy = virDomainDeviceDefCopy(dev, vm->def,
-                                          driver->caps, driver->xmlopt);
+                                          caps, driver->xmlopt);
         if (!dev_copy)
             goto cleanup;
     }
@@ -4668,7 +4736,7 @@ static int lxcDomainDetachDeviceFlags(virDomainPtr dom,
             goto cleanup;
 
         /* Make a copy for updated domain. */
-        vmdef = virDomainObjCopyPersistentDef(vm, driver->caps, driver->xmlopt);
+        vmdef = virDomainObjCopyPersistentDef(vm, caps, driver->xmlopt);
         if (!vmdef)
             goto cleanup;
 
@@ -4709,6 +4777,7 @@ cleanup:
     virDomainDeviceDefFree(dev);
     if (vm)
         virObjectUnlock(vm);
+    virObjectUnref(caps);
     lxcDriverUnlock(driver);
     virObjectUnref(cfg);
     return ret;

src/lxc/lxc_process.c

@@ -986,6 +986,7 @@ int virLXCProcessStart(virConnectPtr conn,
     char *timestamp;
     virCommandPtr cmd = NULL;
     virLXCDomainObjPrivatePtr priv = vm->privateData;
+    virCapsPtr caps = NULL;
     virErrorPtr err = NULL;
     virLXCDriverConfigPtr cfg = virLXCDriverGetConfig(driver);
 
@@ -1027,12 +1028,15 @@ int virLXCProcessStart(virConnectPtr conn,
                     cfg->logDir, vm->def->name) < 0)
         return -1;
 
+    if (!(caps = virLXCDriverGetCapabilities(driver, false)))
+        goto cleanup;
+
     /* Do this up front, so any part of the startup process can add
      * runtime state to vm->def that won't be persisted. This let's us
      * report implicit runtime defaults in the XML, like vnc listen/socket
      */
     VIR_DEBUG("Setting current domain def as transient");
-    if (virDomainObjSetDefTransient(driver->caps, driver->xmlopt, vm, true) < 0)
+    if (virDomainObjSetDefTransient(caps, driver->xmlopt, vm, true) < 0)
         goto cleanup;
 
     /* Run an early hook to set-up missing devices */
@@ -1227,7 +1231,7 @@ int virLXCProcessStart(virConnectPtr conn,
                              conn, lxcProcessAutoDestroy) < 0)
         goto error;
 
-    if (virDomainObjSetDefTransient(driver->caps, driver->xmlopt,
+    if (virDomainObjSetDefTransient(caps, driver->xmlopt,
                                     vm, false) < 0)
         goto error;
 
@@ -1301,6 +1305,7 @@ cleanup:
     VIR_FORCE_CLOSE(handshakefds[1]);
     VIR_FREE(logfile);
     virObjectUnref(cfg);
+    virObjectUnref(caps);
 
     if (err) {
         virSetError(err);