check return codes and print warnings when suspicius

diff --git a/lxcsu b/lxcsu
index 4a5ab6f..a9ff3d6 100755 (executable)
--- a/lxcsu
+++ b/lxcsu
@@ -178,17 +178,23 @@ def main ():
                 exit(1)
 
 
-    setns.chcontext('/proc/%s/ns/uts'%pid)
-    setns.chcontext('/proc/%s/ns/ipc'%pid)
+    def chcontext (path):
+        retcod = setns.chcontext (path)
+        if retcod != 0:
+            print 'WARNING - setns(%s)=>%s (ignored)'%(path,retcod)
+        return retcod
+
+    chcontext('/proc/%s/ns/uts'%pid)
+    chcontext('/proc/%s/ns/ipc'%pid)
        
     if (not args.pidns):
-       setns.chcontext('/proc/%s/ns/pid'%pid)
+       chcontext('/proc/%s/ns/pid'%pid)
 
     if (not args.netns):
-       setns.chcontext('/proc/%s/ns/net'%pid)
+       chcontext('/proc/%s/ns/net'%pid)
 
     if (not args.mntns):
-       setns.chcontext('/proc/%s/ns/mnt'%pid)
+       chcontext('/proc/%s/ns/mnt'%pid)
 
     proc_mounted = False
     if (not os.access('/proc/self',0)):
@@ -210,6 +216,7 @@ def main ():
     for subsystem in ['cpuset','cpu,cpuacct','memory','devices','freezer','net_cls','blkio','perf_event','systemd']:
        fs_path = '/sys/fs/cgroup/%s'%subsystem
        if (not umount(fs_path,'-l')):
+            print 'WARNING - umount failed (ignored) with path=',fs_path
            pass
            # Leaving these comments for historical reference
            #print "Error disabling cgroup access"