xend: Discard error messages of lsscsi

In the case of a host OS without lsscsi command, the following
error message is recorded into xend-debug.log when xend is started.
The error message is recorded once certainly.  If SCSI devices are
connected to the host OS, it is recorded to the number of SCSI
devices.

  sh: lsscsi: command not found

This patch discards the error message to /dev/null.

Signed-off-by: Masaki Kanno <kanno.masaki@jp.fujitsu.com>

tools/python/xen/util/vscsi_util.py

@@ -90,7 +90,7 @@ def _vscsi_get_scsidevices_by_lsscsi(option = ""):
 
     devices = []
 
-    for scsiinfo in os.popen('lsscsi -g %s' % option).readlines():
+    for scsiinfo in os.popen('lsscsi -g %s 2>/dev/null' % option).readlines():
         s = scsiinfo.split()
         hctl = s[0][1:-1]
         try:
@@ -248,7 +248,7 @@ def get_all_scsi_devices():
             get_scsi_scsilevel(scsi_dev['physical_HCTL'])
 
         try:
-            lsscsi_info = os.popen('lsscsi ' + scsi_dev['physical_HCTL']).read().split()
+            lsscsi_info = os.popen('lsscsi %s 2>/dev/null' % scsi_dev['physical_HCTL']).read().split()
             scsi_dev['type'] = lsscsi_info[1]
         except:
             scsi_dev['type'] = None