Add reference counting on virDomainObjPtr objects

Add reference counting on the virDomainObjPtr objects. With the
forthcoming asynchronous QEMU monitor, it will be neccessary to
release the lock on virDomainObjPtr while waiting for a monitor
command response. It is neccessary to ensure one thread can't
delete a virDomainObjPtr while another is waiting. By introducing
reference counting threads can make sure objects they are using
are not accidentally deleted while unlocked.

* src/conf/domain_conf.h, src/conf/domain_conf.c: Add
  virDomainObjRef/Unref APIs, remove virDomainObjFree
* src/openvz/openvz_conf.c: replace call to virDomainObjFree
  with virDomainObjUnref

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 28bee54d519d56bfa31e0d79353e7860a781b1d6..25cb437eff01f13bdd024a2966b00f46d42d1d13 100644 (file)
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -228,7 +228,9 @@ int virDomainObjListInit(virDomainObjListPtr doms)
 static void virDomainObjListDeallocator(void *payload, const char *name ATTRIBUTE_UNUSED)
 {
     virDomainObjPtr obj = payload;
-    virDomainObjFree(obj);
+    virDomainObjLock(obj);
+    if (!virDomainObjUnref(obj))
+        virDomainObjUnlock(obj);
 }
 
 void virDomainObjListDeinit(virDomainObjListPtr doms)
@@ -602,11 +604,12 @@ void virDomainDefFree(virDomainDefPtr def)
 
 #ifndef PROXY
 
-void virDomainObjFree(virDomainObjPtr dom)
+static void virDomainObjFree(virDomainObjPtr dom)
 {
     if (!dom)
         return;
 
+    VIR_DEBUG("obj=%p", dom);
     virDomainDefFree(dom->def);
     virDomainDefFree(dom->newDef);
 
@@ -622,6 +625,25 @@ void virDomainObjFree(virDomainObjPtr dom)
     VIR_FREE(dom);
 }
 
+void virDomainObjRef(virDomainObjPtr dom)
+{
+    dom->refs++;
+    VIR_DEBUG("obj=%p refs=%d", dom, dom->refs);
+}
+
+
+int virDomainObjUnref(virDomainObjPtr dom)
+{
+    dom->refs--;
+    VIR_DEBUG("obj=%p refs=%d", dom, dom->refs);
+    if (dom->refs == 0) {
+        virDomainObjUnlock(dom);
+        virDomainObjFree(dom);
+        return 1;
+    }
+    return 0;
+}
+
 static virDomainObjPtr virDomainObjNew(virConnectPtr conn,
                                        virCapsPtr caps)
 {
@@ -653,7 +675,9 @@ static virDomainObjPtr virDomainObjNew(virConnectPtr conn,
     domain->state = VIR_DOMAIN_SHUTOFF;
     domain->monitorWatch = -1;
     domain->monitor = -1;
+    domain->refs = 1;
 
+    VIR_DEBUG("obj=%p", domain);
     return domain;
 }
 
@@ -3455,7 +3479,7 @@ static virDomainObjPtr virDomainObjParseXML(virConnectPtr conn,
 error:
     VIR_FREE(nodes);
     virDomainChrDefFree(obj->monitor_chr);
-    virDomainObjFree(obj);
+    virDomainObjUnref(obj);
     return NULL;
 }
 
@@ -5052,7 +5076,7 @@ static virDomainObjPtr virDomainLoadStatus(virConnectPtr conn,
     return obj;
 
 error:
-    virDomainObjFree(obj);
+    virDomainObjUnref(obj);
     VIR_FREE(statusFile);
     return NULL;
 }

diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index fadf43f02346e8b7d88a0bcff8e4224f47bcae27..f12c722277cb6c67652e7ad9ff4128bf997f7f03 100644 (file)
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -640,6 +640,7 @@ typedef struct _virDomainObj virDomainObj;
 typedef virDomainObj *virDomainObjPtr;
 struct _virDomainObj {
     virMutex lock;
+    int refs;
 
     int monitor;
     virDomainChrDefPtr monitor_chr;
@@ -697,7 +698,9 @@ void virDomainVideoDefFree(virDomainVideoDefPtr def);
 void virDomainHostdevDefFree(virDomainHostdevDefPtr def);
 void virDomainDeviceDefFree(virDomainDeviceDefPtr def);
 void virDomainDefFree(virDomainDefPtr vm);
-void virDomainObjFree(virDomainObjPtr vm);
+void virDomainObjRef(virDomainObjPtr vm);
+/* Returns 1 if the object was freed, 0 if more refs exist */
+int virDomainObjUnref(virDomainObjPtr vm);
 
 virDomainObjPtr virDomainAssignDef(virConnectPtr conn,
                                    virCapsPtr caps,

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index b360e7126f775e4c41a570306fee5f44abbf2d35..05068672cb09bfa6c7f27b92945bb0c052b4a0ee 100644 (file)
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -123,7 +123,6 @@ virDomainLifecycleTypeToString;
 virDomainLoadAllConfigs;
 virDomainNetDefFree;
 virDomainNetTypeToString;
-virDomainObjFree;
 virDomainRemoveInactive;
 virDomainSaveXML;
 virDomainSaveConfig;
@@ -152,6 +151,8 @@ virDomainObjListGetActiveIDs;
 virDomainObjListNumOfDomains;
 virDomainObjListInit;
 virDomainObjListDeinit;
+virDomainObjRef;
+virDomainObjUnref;
 
 
 # domain_event.h

diff --git a/src/openvz/openvz_conf.c b/src/openvz/openvz_conf.c
index 6eeece899f75053ee2317df12c068c2cdaacacb3..f4c62f33f3644736cadf7d168681351f3846d512 100644 (file)
--- a/src/openvz/openvz_conf.c
+++ b/src/openvz/openvz_conf.c
@@ -463,6 +463,8 @@ int openvzLoadDomains(struct openvz_driver *driver) {
             goto cleanup;
         }
 
+        virDomainObjLock(dom);
+
         if (VIR_ALLOC(dom->def) < 0)
             goto no_memory;
 
@@ -471,6 +473,7 @@ int openvzLoadDomains(struct openvz_driver *driver) {
         else
             dom->state = VIR_DOMAIN_RUNNING;
 
+        dom->refs = 1;
         dom->pid = veid;
         dom->def->id = dom->state == VIR_DOMAIN_SHUTOFF ? -1 : veid;
 
@@ -513,6 +516,7 @@ int openvzLoadDomains(struct openvz_driver *driver) {
         if (virHashAddEntry(driver->domains.objs, uuidstr, dom) < 0)
             goto no_memory;
 
+        virDomainObjUnlock(dom);
         dom = NULL;
     }
 
@@ -525,7 +529,7 @@ int openvzLoadDomains(struct openvz_driver *driver) {
 
  cleanup:
     fclose(fp);
-    virDomainObjFree(dom);
+    virDomainObjUnref(dom);
     return -1;
 }