[libvirt] [PATCHv3] qemu: fix unsuitable error report when get memory stats

[Wang Yufei]

From: Zhang Bo <oscar.zhangbo at huawei.com>

when we run the command 'virsh dommemstat xxx',
althrough memballoon's model is set 'none' in vm's XML,
it still reports an error in libvirtd.log.
error : qemuMonitorFindBalloonObjectPath:1042 : internal error: Cannot determine balloon device path
Apparently, if we don't set memballoon, we don't need to
set balloon device path.

Signed-off-by: Wang Yufei <james.wangyufei at huawei.com>
Signed-off-by: Zhang Bo <oscar.zhangbo at huawei.com>
---
 src/qemu/qemu_monitor.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index f959b74..8c3c6f3 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1169,8 +1169,10 @@ qemuMonitorFindBalloonObjectPath(qemuMonitorPtr mon,
     if (mon->balloonpath) {
         return 0;
     } else if (mon->ballooninit) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Cannot determine balloon device path"));
+        if (vm->def->memballoon && 
+            vm->def->memballoon->model != VIR_DOMAIN_MEMBALLOON_MODEL_NONE)
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Cannot determine balloon device path"));
         return -1;
     }
 
-- 
1.7.12.4