[PATCH] xend: make xc.vcpu_getinfo() return None if guest not existed

[Joe Jin <joe.jin@oracle.com>]

We hit failure when when reboot some guests at the same time,
xend.log has below:
[2013-09-04 20:01:26 6254] ERROR (XendDomainInfo:496) VM start failed
Traceback (most recent call last):
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 482, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendTask.py", line 209, in log_progress
    retval = func(*args, **kwds)
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 2918, in _initDomain
    node = self._setCPUAffinity()
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 2835, in _setCPUAffinity
    best_node = find_relaxed_node(candidate_node_list)[0]
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 2803, in find_relaxed_node
    cpuinfo = dom.getVCPUInfo()
  File "/usr/lib64/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1600, in getVCPUInfo
    raise XendError(str(exn))
XendError: (3, 'No such process')

This caused by one or more guests be rebooted between the call of
find_relaxed_node()->list('all') and getVCPUInfo(). This patch will let
xc.vcpu_getinfo() return None if guest not existed to avoid the failure.

Signed-off-by: Joe Jin <joe.jin@oracle.com>
Cc: Matt Wilson <msw@amazon.com>
Cc: Keir Fraser <keir@xen.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Roger Pau Monne <roger.pau@citrix.com>
---
 tools/python/xen/lowlevel/xc/xc.c       |   15 ++++++++++++---
 tools/python/xen/xend/XendDomainInfo.py |    2 +-
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/tools/python/xen/lowlevel/xc/xc.c b/tools/python/xen/lowlevel/xc/xc.c
index 2625fc4..9a7e589 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -396,8 +396,13 @@ static PyObject *pyxc_vcpu_getinfo(XcObject *self,
         return pyxc_error_to_exception(self->xc_handle);
 
     rc = xc_vcpu_getinfo(self->xc_handle, dom, vcpu, &info);
-    if ( rc < 0 )
-        return pyxc_error_to_exception(self->xc_handle);
+    if ( rc < 0)
+    {
+        if (errno == ESRCH)
+            return Py_BuildValue("");
+        else
+            return pyxc_error_to_exception(self->xc_handle);
+    }
 
     cpumap = xc_cpumap_alloc(self->xc_handle);
     if(cpumap == NULL)
@@ -407,7 +412,11 @@ static PyObject *pyxc_vcpu_getinfo(XcObject *self,
     if ( rc < 0 )
     {
         free(cpumap);
-        return pyxc_error_to_exception(self->xc_handle);
+
+        if (errno == ESRCH)
+            return Py_BuildValue("");
+        else
+            return pyxc_error_to_exception(self->xc_handle);
     }
 
     info_dict = Py_BuildValue("{s:i,s:i,s:i,s:L,s:i}",
diff --git a/tools/python/xen/xend/XendDomainInfo.py b/tools/python/xen/xend/XendDomainInfo.py
index e9d3e7e..6b5fd83 100644
--- a/tools/python/xen/xend/XendDomainInfo.py
+++ b/tools/python/xen/xend/XendDomainInfo.py
@@ -1518,7 +1518,7 @@ class XendDomainInfo:
             for i in range(0, self.info['VCPUs_max']):
                 if self.domid is not None:
                     info = xc.vcpu_getinfo(self.domid, i)
-
+                    if info == None: continue
                     sxpr.append(['vcpu',
                                  ['number',   i],
                                  ['online',   info['online']],
-- 
1.7.1