Re: [Xen-API] race condition during /etc/xensource/scripts/vif call

[George Shuklin <george.shuklin@xxxxxxxxx>]

Ok, may be I was wrong and shall not use any /xapi keys on interface 
remove. Right now I switched from xapi usage to '$vsctl port-to-br'. But 
any way, this is kinda strange - why /xapi entery dissapear before 
interface completely shutdown?
On 23.09.2011 03:07, Jonathan Ludlam wrote:
> Interesting - it might be that you're racing with xapi - it's waiting for the 
> hot plug key to be removed, which is what the xenstore-rm does. Have a look 
> here:
>
> https://github.com/xen-org/xen-api/blob/master/ocaml/xenops/device.ml#L752
>
> (Note that this is more current than XCP 1.0 or 1.1, but the general gist is 
> the same)
>
> Jon
>
> On 22 Sep 2011, at 16:18, George Shuklin wrote:
>
> > Good day.
> >
> > Found strange situation for VM with two or more interfaces: data
> > from /xapi for domain disappear before vif remove called second time.
> >
> > Here little patch to vif script (against XCP 1.1 beta) to log XenStore
> > state:
> >
> > --- vif.orig    2011-05-19 02:32:19.000000000 +0400
> > +++ vif 2011-09-22 19:11:10.000000000 +0400
> > @@ -227,6 +227,8 @@
> >          xenstore-rm "${HOTPLUG}/hotplug"
> >      fi
> >      logger -t scripts-vif "${dev} has been removed"
> > +    echo ====domid=$DOMID=====>>/var/log/vif-race.log
> > +    xenstore-ls /xapi>>/var/log/vif-race.log
> >      remove_from_bridge
> >      ;;
> > esac
> >
> >
> > To see 'strange' add to any vm two interfaces and reboot it.
> >
> > In vif-race.log for second time vif call:
> > ====domid=3=====
> > 0 = ""
> > hotplug = ""
> >   vbd = ""
> > private = ""
> >   vbd = ""
> >    51712 = ""
> >     ref = "OpaqueRef:1a7992ae-a645-acc6-bf51-3a0202bdd4c7"
> > frontend = ""
> >   vbd = ""
> > 3:
> >
> > (no data for domid 3).
> >
> > I'm not sure if this is a really serious bug, but I found my
> > antispoofing patch does not remove rules from OVS for multihomed VM's
> > due lack of 'bridge' variable for VIF (I'm calling remove_restiction()
> > function in 'remove' case in vif script).
> >
> > I got this bug in XCP 1.0 and XCP1.1 beta.
> >
> >
> >
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