Re: [Xen-devel] Test Xen 4.8 RC4 not stable 27.10.16

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 10/28/2016 11:30 AM, Wei Liu wrote:
> On Fri, Oct 28, 2016 at 04:01:54PM +0100, Juergen Schinker wrote:
>>
>> ----- On 28 Oct, 2016, at 13:07, Boris Ostrovsky boris.ostrovsky@xxxxxxxxxx 
>> wrote:
>>
>>> I believe at least on some distros /var/run should be soft-linked to
>>> /run, otherwise whoever cleans up those directories (the command name
>>> escapes me right now) will only remove files from /run and leave
>>> /var/run (and therefore /var/run/xen/xenstored.pid) untouched.
>>>
>>> And because xencommons checks for existence of this this file before
>>> starting xenstored the latter never starts.
>>>
>>> -boris
>> root@xen:~# ls -la /var/run/xen/xenstored.pid 
>> -rw-r----- 1 root root 6 Oct 28 15:15 /var/run/xen/xenstored.pid
>>
>>   
>>    33 ?        00:00:00 xenwatch
>>    34 ?        00:00:00 xenbus
>>    45 ?        00:00:00 xenbus_frontend
>>   785 ?        00:00:00 xen_pciback_wor
>>  1137 ?        00:00:00 xenwatchdogd
>>  1169 ?        00:00:00 xen-init-dom0
>>  1175 ?        00:00:00 xenconsoled
>>
>> Thats exactly what I'm sayin , maybe we need a more intelligent check to see 
>> if xenstored is running
>>
>> not just a simple pid check
>>
> But ... the pid check is the usual way of checking if a daemon is
> active.
>
> I think a bit work is required to work out why xenstored.pid stays
> across reboot -- it is not supposed to work like that on a FHS compliant
> system.

I remember now: it's systemd-tmpfiles that creates and cleans up those
files. I think the way it works is it checks
/usr/lib/tmpfiles.d/var.conf for the rules. On my fedora24:

L /var/run - - - - ../run

Which IIUIC means that /var/run should be linked to ../run (i.e. /run)
during boot. Or something along these lines. Perhaps because when we
shut down xenstored.pid is still there and so the link cannot be made.


-boris

>
> And how do other daemons work on your test host, presumably they will
> see stale pid files as well.  Are there any other pid files under
> /var/run? If so, do the corresponding daemon run properly?
>
> Wei.
>
>> J


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