qemu: fix nwfilter deadlock in qemuProcessReconnect

The correct lock order is:

  nwfilter driver lock (not used in this code path)
  nwfilter update lock
  virt driver lock (not used in this code path)
  domain object lock

but the current code have this order:

  domain object lock
  nwfilter update lock
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

src/qemu/qemu_process.c

@@ -6813,8 +6813,6 @@ qemuProcessReconnect(void *opaque)
     if (qemuDomainMasterKeyReadFile(priv) < 0)
         goto error;
 
-    virNWFilterReadLockFilterUpdates();
-
     VIR_DEBUG("Reconnect monitor to %p '%s'", obj, obj->def->name);
 
     /* XXX check PID liveliness & EXE path */
@@ -7043,6 +7041,8 @@ qemuProcessReconnectHelper(virDomainObjPtr obj,
     memcpy(data, src, sizeof(*data));
     data->obj = obj;
 
+    virNWFilterReadLockFilterUpdates();
+
     /* this lock and reference will be eventually transferred to the thread
      * that handles the reconnect */
     virObjectLock(obj);
@@ -7068,6 +7068,7 @@ qemuProcessReconnectHelper(virDomainObjPtr obj,
         qemuDomainRemoveInactive(src->driver, obj);
 
         virDomainObjEndAPI(&obj);
+        virNWFilterUnlockFilterUpdates();
         virObjectUnref(data->conn);
         VIR_FREE(data);
         return -1;