linux_stress: stress app should not be killed

Stress app should not be killed without stress_duration defined
Signed-off-by: NQianqian Zhu <qizhu@redhat.com>

generic/tests/linux_stress.py

@@ -11,8 +11,8 @@ def run(test, params, env):
     General stress test for linux:
        1). Install stress if need
        2). Start stress process
-       3). If no stress_time defined, keep stress until test_timeout;
-       otherwise execute below steps after sleeping stress_time long
+       3). If no stress_duration defined, keep stress until test_timeout;
+       otherwise execute below steps after sleeping stress_duration long
        4). Stop stress process
        5). Uninstall stress
        6). Verify guest kernel crash
@@ -45,7 +45,6 @@ def run(test, params, env):
 
     if stress_duration:
         time.sleep(stress_duration)
-
         for vm in vms:
             try:
                 s_ping, o_ping = utils_test.ping(vm.get_address(), count=5, timeout=20)