Bug 955543

Description of problem:
According to comment14 &&15 BZ#849315, so it's better that rewrite "the reboot implementation" 
instead of using crond for the async reboot.
But actually, in rhev-h 6.4, it still used old method about "the reboot implementation"

          if reboot is not None and reboot == "Y":
                f = open('/var/spool/cron/root', 'w')
                f.write('* * * * * sleep 10 && /sbin/reboot\n')
                f.close()
                #ensure crond is started
                _functions.subprocess_closefds("crond", shell=True,
                                    stdout=subprocess.PIPE,
                                    stderr=subprocess.STDOUT)

it's better to using this method of Alon Bar-Lev mentioned：
http://gerrit.ovirt.org/gitweb?p=vdsm.git;a=blob;f=vdsm_reg/deployUtil.py.in;hb=HEAD#l202

Seem that this new "reboot implementation" is more considerate and may avoid potential issues
caused by the crude reboot.


#!/usr/bin/env python
import os
import sys
import time

def simpleDaemon(main, args=(), kwargs={}):
        # Default maximum for the number of available file descriptors.
        MAXFD = 1024

        import resource  # Resource usage information.
        maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
        if (maxfd == resource.RLIM_INFINITY):
            maxfd = MAXFD

        pid = os.fork()
        if pid == 0:
            try:
                os.setsid()
                for fd in range(0, maxfd):
                    try:
                        os.close(fd)
                    except OSError:
                        # ERROR, fd wasn't open to begin with (ignored)
                        pass

                os.open(os.devnull, os.O_RDWR)  # standard input (0)
                os.dup2(0, 1)  # standard output (1)
                os.dup2(0, 2)  # standard error (2)

                if os.fork() != 0:
                    os._exit(0)

                try:
                    main(*args, **kwargs)
                except:
                    import traceback
                    traceback.print_exc()
            finally:
                os._exit(1)

        pid, status = os.waitpid(pid, 0)

        if not os.WIFEXITED(status) or os.WEXITSTATUS(status) != 0:
            raise RuntimeError('Daemon not exited properly')

def delayedReboot(reboot, sleepTime): 
        time.sleep(sleepTime)
        os.execl(reboot, reboot)

def reboot( delay):
        simpleDaemon(
            delayedReboot,
            (
                "/sbin/reboot",
                delay,
            )
        )

reboot(10)


Version-Release number of selected component (if applicable):
rhev-hypervisor6-6.4-20130415.0.el6_4

How reproducible:
100% 
 
Steps to Reproduce:


Actual result:          
                                                  
Expect result:


Additional info: