[libvirt] [PATCH 1/3] libxl: lock virDomainObj after ListRemove

[Jim Fehlig]

Most libxl driver API use the pattern of lock and add a ref to
virDomainObj, perform API, then decrement ref and unlock in
virDomainEndAPI. In some cases the API may call
virDomainObjListRemove, which unlocks the virDomainObj. Relock
the object in such cases so EndAPI is called with a locked object.

Signed-off-by: Jim Fehlig <jfehlig at suse.com>
---
 src/libxl/libxl_driver.c    | 22 +++++++++++++---------
 src/libxl/libxl_migration.c |  7 +++++--
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index 89432d03c..ac61fb322 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -1056,7 +1056,7 @@ libxlDomainCreateXML(virConnectPtr conn, const char *xml,
     if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_MODIFY) < 0) {
         if (!vm->persistent) {
             virDomainObjListRemove(driver->domains, vm);
-            vm = NULL;
+            virObjectLock(vm);
         }
         goto cleanup;
     }
@@ -1065,7 +1065,7 @@ libxlDomainCreateXML(virConnectPtr conn, const char *xml,
                          (flags & VIR_DOMAIN_START_PAUSED) != 0) < 0) {
         if (!vm->persistent) {
             virDomainObjListRemove(driver->domains, vm);
-            vm = NULL;
+            virObjectLock(vm);
             goto cleanup;
         }
         goto endjob;
@@ -1417,8 +1417,10 @@ libxlDomainDestroyFlags(virDomainPtr dom,
                                      VIR_DOMAIN_EVENT_STOPPED_DESTROYED);
 
     libxlDomainCleanup(driver, vm);
-    if (!vm->persistent)
+    if (!vm->persistent) {
         virDomainObjListRemove(driver->domains, vm);
+        virObjectLock(vm);
+    }
 
     ret = 0;
 
@@ -1822,7 +1824,7 @@ libxlDomainSaveFlags(virDomainPtr dom, const char *to, const char *dxml,
  cleanup:
     if (remove_dom && vm) {
         virDomainObjListRemove(driver->domains, vm);
-        vm = NULL;
+        virObjectLock(vm);
     }
     virDomainObjEndAPI(&vm);
     return ret;
@@ -1877,7 +1879,7 @@ libxlDomainRestoreFlags(virConnectPtr conn, const char *from,
     if (libxlDomainObjBeginJob(driver, vm, LIBXL_JOB_MODIFY) < 0) {
         if (!vm->persistent) {
             virDomainObjListRemove(driver->domains, vm);
-            vm = NULL;
+            virObjectLock(vm);
         }
         goto cleanup;
     }
@@ -1885,8 +1887,10 @@ libxlDomainRestoreFlags(virConnectPtr conn, const char *from,
     ret = libxlDomainStartRestore(driver, vm,
                                   (flags & VIR_DOMAIN_SAVE_PAUSED) != 0,
                                   fd, hdr.version);
-    if (ret < 0 && !vm->persistent)
+    if (ret < 0 && !vm->persistent) {
         virDomainObjListRemove(driver->domains, vm);
+        virObjectLock(vm);
+    }
 
     libxlDomainObjEndJob(driver, vm);
 
@@ -1995,7 +1999,7 @@ libxlDomainCoreDump(virDomainPtr dom, const char *to, unsigned int flags)
  cleanup:
     if (remove_dom && vm) {
         virDomainObjListRemove(driver->domains, vm);
-        vm = NULL;
+        virObjectLock(vm);
     }
     virDomainObjEndAPI(&vm);
     if (event)
@@ -2056,7 +2060,7 @@ libxlDomainManagedSave(virDomainPtr dom, unsigned int flags)
  cleanup:
     if (remove_dom && vm) {
         virDomainObjListRemove(driver->domains, vm);
-        vm = NULL;
+        virObjectLock(vm);
     }
     virDomainObjEndAPI(&vm);
     VIR_FREE(name);
@@ -2880,7 +2884,7 @@ libxlDomainUndefineFlags(virDomainPtr dom,
         vm->persistent = 0;
     } else {
         virDomainObjListRemove(driver->domains, vm);
-        vm = NULL;
+        virObjectLock(vm);
     }
 
     ret = 0;
diff --git a/src/libxl/libxl_migration.c b/src/libxl/libxl_migration.c
index 7dc39ae02..324a1adde 100644
--- a/src/libxl/libxl_migration.c
+++ b/src/libxl/libxl_migration.c
@@ -299,7 +299,7 @@ libxlDoMigrateReceive(void *opaque)
  cleanup:
     if (remove_dom) {
         virDomainObjListRemove(driver->domains, vm);
-        vm = NULL;
+        virObjectLock(vm);
     }
     virDomainObjEndAPI(&vm);
 }
@@ -1336,8 +1336,11 @@ libxlDomainMigrationFinish(virConnectPtr dconn,
                              VIR_DOMAIN_SHUTOFF_FAILED);
         event = virDomainEventLifecycleNewFromObj(vm, VIR_DOMAIN_EVENT_STOPPED,
                                          VIR_DOMAIN_EVENT_STOPPED_FAILED);
-        if (!vm->persistent)
+        if (!vm->persistent) {
             virDomainObjListRemove(driver->domains, vm);
+            /* Caller passed a locked vm and expects the same on return */
+            virObjectLock(vm);
+        }
     }
 
     if (event)
-- 
2.16.2